Cell-Therapy Safety: Infection, Immune Reactions and Unwanted Tissue Effects

If you have had a cell injection or infusion and feel worse

These can be signs of the problems described below. Get medical care right away if you develop fever, chills, severe or worsening pain, redness, swelling or drainage at a treatment site, a sudden change in vision, new weakness or numbness, or a severe headache after a stem cell, exosome or similar procedure. In the United States, call 911 for an emergency. Tell the clinicians treating you exactly what was given, where it was given and by whom. The FDA says life-threatening bloodstream infections and neurological events have been reported with unapproved regenerative products. [1] The FDA also asks patients or clinicians to report problems to its MedWatch program; details are at the end of this page. [2]

This page is information only. It does not tell anyone to start or stop a treatment, and it does not replace advice from a clinician who knows your health.

What "cell therapy" safety covers here

"Cell therapy" means giving living cells, or products made from cells, to treat a condition. Some are approved medicines with known risks and monitoring. Others are sold by clinics without regulatory approval. This page keeps the two apart. For background on terms, see stem cells explained and autologous vs allogeneic cell products. Evidence labels used below are explained in how we label evidence.

Risks the FDA lists for unapproved regenerative products

The FDA says products illegally marketed as regenerative medicine therapies carry risks that include blindness, tumor formation, neurological events, bacterial infections (including life-threatening blood infections), reactions where cells were collected or given, and an unwanted inflammatory or immune response to the cells. [1] It also lists cells moving to another part of the body and turning into an unintended type of tissue or growing excessively, and cross-contamination with bacteria, viruses or mold, or products not tested for infections such as hepatitis and HIV. [1]

The FDA states that it has received reports of blindness, tumor formation and infections linked to these unapproved products. [1] These are regulator-collected reports, so they show harm can happen but do not give how often.

Own cells are not automatically safe

The ISSCR (a professional society of stem cell scientists) notes that using a person's own cells in theory avoids immune attack, but the steps of collecting, growing and returning the cells carry risk. [3] It lists contamination with viruses or bacteria, interference from lab handling with normal cell growth control, and cells placed where they do not belong. [3] The FDA's list of unapproved products that need its oversight includes stem cells, fat-derived cells, cord blood, amniotic fluid, Wharton's jelly and exosomes, whether recovered from your own body or another person's. [1] See regulatory status for the exact test.

Published case reports

Case reports show real harms but cannot show how common they are.

• Eye (intravitreal injection): three patients developed severe vision loss in both eyes after receiving injections of fat-derived "stem cells" at one US clinic. Problems included raised eye pressure, bleeding and retinal detachment, and after one year vision ranged from 20/200 to no light perception. [4] Evidence level: case series, evidence of harm.
• Brain tumor after neural stem cell treatment: a boy with ataxia telangiectasia was given fetal neural stem cells into the cerebellum and spinal fluid space. Four years later he was diagnosed with a multifocal brain tumor, and testing showed it came from at least two donors. [5] Evidence level: single case, evidence of harm.
• Nerve root swelling after infusion into the spinal fluid space: a case report describes inflammatory enlargement of the cauda equina nerve roots after intrathecal stem cell infusion, and notes other reported events such as neoplasms, demyelinating disease and seizures. [6]

A broader review of case reports and media reports found that unproven stem cell products have caused reported safety incidents, and examined why "stem cell tourism" has grown. [7] Proper evidence not found for reliable complication rates per product or per clinic: no registry covering unapproved clinics was found in the sources read.

Approved cell products also have risks

Safety is not only an "unapproved" issue. Ryoncil, an FDA-approved donor-derived mesenchymal stromal cell therapy for children (2 months and older) with steroid-refractory acute graft-versus-host disease, lists infections, fever, hemorrhage, edema, abdominal pain and hypertension as the most common adverse reactions. [8] The FDA also lists hypersensitivity and infusion reactions, transmission of infectious agents and ectopic tissue formation as possible complications, and the product is contraindicated for people with known hypersensitivity to dimethyl sulfoxide or porcine and bovine proteins. [8] The difference is that approved products come with oversight, labeling, monitoring and a defined patient group. See cell-therapy clinical trials vs commercial treatments.

A treatment that does not work can also cause harm

The FDA lists "failure of the therapy to work as anticipated when approved treatments are available" among the risks. [1] The ISSCR adds that receiving one unproven treatment may make a person ineligible for future clinical trials, and costs can be large and are usually not covered by insurance. [3]

Talk with your own specialist first

Before any cell-based procedure, discuss it with a specialist who treats your condition and who is not selling the procedure. Ask whether it is part of an FDA-overseen clinical trial or an approved product; see unapproved clinics and medical tourism for the questions regulators suggest.

How to report a problem

Report to the FDA's MedWatch program, including the product type or name, the clinic, when it happened and whether the cells were your own (autologous) or a donor's (allogeneic); partial information is still useful. [2] General guidance on reporting problems is in reporting adverse events from therapies.